A. Field of the Invention
The present invention relates to a cooling system and method for a portable computer. More particularly, it is a cooling system and method which can automatically switch a Central Processing Unit (hereinafter referred to as CPU) to a proper execution mode according to a current working temperature and an air flow value, thereby to prevent the CPU from overheating.
B. Description of the Prior Art
High speed CPU, such as Pentium CPU, requires special cooling devices for heat dissipation and heat absorption, such as cooling plate, cooling fans, and cooling fins, etc. However, the heat dissipation functions of these devices are very limited for a portable computer mainly due to the size of the compact housing. To fit into the compact housing, the cooling fan must be made smaller and thinner than an ordinary one used in a desktop computer. Consequently, the fan is not powerful enough to efficiently dissipate the heat generated by the CPU. The situation is the same when using cooling plate and cooling fins of smaller sizes.
Moreover, the housing of a portable computer is so compact that it barely leaves room for heat dissipation. For the concern of damages caused by overheating, some portable computers use thermal sensors for detecting a working temperature inside the housing. When the thermal sensor detects that the temperature is rising up abnormally, then it will slow down the system performance by adjusting the working frequency and voltage of the system to a lower execution mode of low heat generation state in order to cool down the CPU. In contrast, in an air-conditioned room or a room of good ventilation where the working temperature is usually below a normal working temperature, then the system can be switched to a higher execution mode by increasing the working frequency and voltage of the system so that the system performance can be increased.
However, the temperature control is not only a matter of temperature detection and execution mode switching. It should also involve in the control over the ventilation system and CPU execution mode to reach a high efficiency of heat dissipation in case of serious overheating. According to the conventional technology, the system cannot respond to the temperature change instantly and directly because it cannot establish a connection between the ventilation system and the CPU and then enhancing air flow while switching the CPU to a lower execution mode and vice versa.